1. Field of the Invention
The present invention relates to a hard disk drive and, more particularly, to a hard disk drive for controlling the flow of air to thereby reduce the head's vibration and accordingly to enhance the performance of head in read/write.
2. Description of the Related Art
A hard disk drive (HDD) is a data storage device of a computer and records or reproduces data stored on a disk using a read/write head. In the HDD, a head performs the recording or reproducing function while being lifted from the recording surface of a rotating disk by a predetermined height and moved to a desired location by an actuator.
FIG. 1 is a schematic perspective view of one example of a conventional HDD. FIG. 2 is a longitudinal vertical section of the HDD shown in FIG. 1. Referring to FIGS. 1 and 2, the HDD is equipped with a housing 10 consisting of a base member 11 and a cover member 12A; a spindle motor 30 is provided on the base member 11. At least one disk 20 is fixedly installed on the spindle motor 30. An actuator 40 is included for moving a read/write head (not shown) for data recording/reproducing to a predetermined location on the disk 20.
The spindle motor 30 is supported by a flange 31 fixedly installed on the base member 11. A shaft 32 of the spindle motor 30 is fixed to the cover member 12 to which the top end of the shaft is usually coupled by a screw 36. A bearing 37 is installed between the shaft 32 and a hub 33 to which the disk 20 is fitted. When a plurality of disks 20 are mounted, a ring-shaped spacer 34 for maintaining the distance between the disks 20 is placed on the hub 33. A clamp 35 for clamping the disks 20 is coupled to the top end of the hub 33.
The actuator 40 includes a swing arm 44 rotatably coupled to a pivot bearing 42 installed on the base member 11, a suspension 46 provided on one end of the swing arm 44 for elastic-biasing the slider 48 toward the surface of the disk 20, and a voice coil motor (VCM) 50.
When the HDD is turned on and the disk 20 starts to rotate in the direction of an arrow D, the VCM 50 causes the swing arm 44 to rotate to move the slider 48 above the recording surface of the disk 20. The slider 48 is lifted from the surface of the disk 20 by a predetermined height due to a lifting force produced by the rotating disk 20. In this condition, the head mounted on the slider 48 writes data on or reads data from the disk 20.
When the HDD does not work or the disk 20 stops rotating, the head is prevented from colliding with the disk 20 by being landed on a location apart from the recording surface of the disk 20. For this purpose, a parking zone 21, where the slider 48 parks when the power is OFF, is provided in an inner circumferential side of the disk 20, and a data zone 22, where data is written, is provided in an outer circumferential side of the disk 20.
Recently, the data storage capacity and rotation speed of HDDs have considerably increased. The data storage capacity of a HDD is proportional to a surface recoding density, which is determined by the product of a linear recording density indicated as BPI (bits per inch) and the track density indicated as TPI (tracks per inch). Whereas BPI has been increased based on newly developed magnetic recording technology, TPI has been generally increased by enhancing the mechanical dynamic characteristics of the HDD.
In the conventional HDD shown in FIG. 2, the distance between the lower disk 20 and the base member 11 and the distance between two disks 20 are sufficiently narrow, but the distance between the upper disk 20 and the cover member 12 is comparatively wide. Generally, an elevated plane 13 protruding toward the disk 20 is formed on the base member 11, to render the distance between the disk 20 and the base member 11 narrower. Therefore, between the base member 11 and the lower disk 20 and two disks 20, an almost laminar air flow is caused by the rotation of the disks 20, and the amount of air supplied to the suspension 46 and the slider 48 of the actuator 40 is relatively small, thereby reducing the impact of the air flow on the slider 48.
However, because the distance between the upper disk 20 and the cover member 12 is relatively wide, the air flow caused by the rotation of the disk 20 becomes turbulent and the amount of flowing air is relatively large. This aggravates the impact of the air flow on the suspension 46 and the slider 48 of the actuator 40. Accordingly, the head mounted on the slider 48 starts to vibrate, thereby decreasing the servo control tracking accuracy and deteriorating the read/write performance of the head.
To solve this problem, Japanese Patent Application Laid-open Publication No. 2001-338482 discloses an HDD having a thin plate attached to the bottom of a cover member to reduce a distance between the plate and a disk in order to repress disk fluttering. Such a structure only reduces disk fluttering but does not prevent the air flow from hitting the head. To this end, the publication proposes a barrier placed outside the disk, which, however, acts to control the air flow toward the head from the actuator but does not block the air flow formed between the disk and the cover member.